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XXXIV. — TJie Chemical and Bacteriological Examination of Soil, with special refer- 

 ence to the Soil of Graveyards. By James Buchanan Young, M.B., D.Sc. 

 (From the Public Health Laboratory, University of Edinburgh.) 



(Read 28th May 1894.) 



The research which forms the subject of this paper was undertaken in the hope that 

 it might throw some additional light on the numerical relation existing between the 

 bacteria present at various depths in ordinary soils, and in soils which had been used for 

 purposes of interment. It was thought well to combine the chemical with the bacterio- 

 logical examination for the purpose of determining to what extent the amount of organic 

 matter present in the two classes of soil differed, and in what respect the organic matter 

 of the one was different from that of the other, as well as to ascertain, if possible, to 

 what extent the process of self-purification goes on in soil which has been used for 

 burial. 



The examination of soil, both chemically and bacteriologically, presents difficulties 

 which have been so thoroughly appreciated that but little work has been done on the 

 subject in this country. The great difficulty of getting reliable samples, and the difficul- 

 ties associated with the investigation of the samples when obtained, have doubtless been 

 the deterrent factors. 



Many and various methods have been suggested and employed for the bacteriological 

 examination of soil, with more or less success. The method which I have employed, and 

 which I had formerly found to give very satisfactory and consistent results, is that 

 devised by Professor Hueppe, formerly of Wiesbaden, now of Prague. For the estima- 

 tion of the organic matter in the samples I employed Dr Hunter Stewart's modifi- 

 cation of the Kjeldahl process, and I have found it to work most satisfactorily. 



Collection of Samples. — The samples of soil for bacteriological examination were in 

 all cases taken from graves which were being opened for burial, or from freshly opened 

 ground. All samples were taken from a clean and freshly-cut surface of soil by means of 

 a sterilised knife, digging well in, so as to avoid surface contamination. Having cut out 

 a sufficiently large sample, it was at once transferred to a sterile Foster's box, which was 

 again placed in a tin case previously sterilised by washing with a solution of perchloride 

 of mercury (1 in 1000). In this tin case the glass capsule (Foster's box) rested on a 

 sheet of coarse filter-paper, soaked in corrosive sublimate solution, covering the entire 

 bottom of the case. In such cases the samples were at once removed to the laboratory 

 and their examination proceeded with. The bacteriological examination was in all cases 



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